Adaptogens is a term used to describe pharmacological agents (usually herbs) that possess a wide range of regulatory activity, but which manifest their actions only against an actual challenge (stress) to the body; and which act via non-specific mechanisms to increase the non-specific resistance to harmful influences of an extremely wide spectrum of physical, chemical and biological factors that cause stress.

Adaptogens are so named due to their ability to exert a normalising action irrespective of the direction of pathological changes (for instance, Adaptogens may lower blood pressure in persons with high blood pressure, while raising blood pressure in persons afflicted with low blood pressure).

Only 3 plants have been approved by the world's leading experts as possessing all of the criteria required to be called a 'pure' Adaptogen. These are Rhodiola Rosea, Eleutherococcus Senticosus and Schisandra Chinensis. 

While many substances have adaptogenic properties, in order to be classified as an Adaptogen, the plants must be proven to possess the following 4 criteria:

1. must be non-toxic and completely harmless to the body - 100% natural
2. must exert a normalising influence on the body
3. must possess a wide range of therapeutic benefits - non-specific
4. must cause little or no disturbance to the normal functioning of the body

Adaptogens are available as health supplements or as an ingredient in some health and nutrition supplements.